Presentation of a CASCON 2009 paper: Business process modeling has been a promising direction in developing service compositions, including both service orchestrations and choreographies. This paper fully focuses on the problem of modeling service orchestrations. Despite many promising aspects of using business process modeling (BPM) languages for modeling service orchestrations, this paper aims to demonstrate that: i) best practices (workflow patters) for control flows (primary concern of service orchestrations) are not fully covered in present languages; ii) complete service compositions cannot be completely generated from business process models; and iii) BPM languages have limited support for representing logical expressions, business vocabularies, and business rules, which severely limits their flexibility and expressiveness. To address these challenges, we have integrated business rule mod-eling constructs of the REWERSE Rule Markup Language (R2ML) with the Business Process Modeling Notation (BPMN), resulting in our rBPMN proposal.